Casebook 2011: Automatic guided vehicles replaces aging rail car

Northrop Grumman, a designer and builder of nuclear-powered aircraft carriers and submarines and provider of aftermarket services to an array of naval and commercial vessels, was having trouble locating parts for its rail car and maintenance costs were escalating. When expanding its facility in 2004, instead of going with the aged rail car technology it was using, engineers installed an automatic guided vehicle (AGV; Jervis B. Webb Company, 248-553-1000, [url=http://www.jervisbwebb.com]http://www.jervisbwebb.com[/url]) with far more locomotion.

Prior to 2004, the company used a roller conveyor that carried primed plates from the plate prep building to a 30-year-old rail car that carried plates to each of six trimming stations. As production increased, the company built an additional station in another facility that would have required the rail car to travel a 90-degree bend.

Instead, the company installed a new, laser-guided AGV to replace the rail car. The battery-powered AGV not only replaced embedded steel rails in the floor, but also the trailing AC cord apparatus. With four-wheel drive and independent steering, the new AGV travels in any direction, inside and outside the facility. The AGV operates automatically according to programmed instructions from the operator, using laser-scanning system at each end of the vehicle to detect people and objects.

The company’s new plate transport system moves large steel plates varying from 3/16 of an inch to 2 inches thick and up to 14 feet wide by 50 feet long. The largest of these plates can weigh nearly 20 tons. The AGV is capable of straddling a stack of plates up to 18 inches high, allowing it to travel over the stack to deliver to other locations.

“The uniqueness of this AGV is that it has a powered roller deck on top to roll the plates off,” says project engineer John Chilbert, who also says the company is considering other possible AGV applications. “As we replace our older materials handling systems, we want to replace them with the best new technology available.”